The amino acids are the building blocks of proteins and act as intermediates in body metabolism. The importance of amino acids as building blocks of proteins for the growth and repair of muscles, bones, skin, tendons, ligaments, hair, eyes and other tissues is proven since a very long time. Proteins play a vital role in various body functions such as, metabolism, cell signalling, the immune system, cell adhesion and cell cycle. The problem of protein deficiency is very common among populations of poor, undeveloped and in developing countries. Even in developed nations, this problem of protein deficiency was reported in certain groups of population with specific diet habits. Particularly, vegetarians need to be very careful about eating the right combinations of plant foods to get enough of the essential amino acids. When proteins enter the body; first they are broken down into amino acids during the digestion process. The amino acids are then used in different areas of the body where they are needed for protein synthesis. The amino acids are also responsible for the biological activities of proteins. So, the amino acids which are the building blocks of proteins are vital for body functioning. So there exist huge potential of using amino acids in form of nutritional supplements.
Generally there are 20 standard amino acids which constitute the proteins, and out of these only 10 are synthesized in our body. The other 10 which are not synthesized in our body are called as essential amino acids viz. alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. We need to obtain these essential amino acids from our diet and failure to obtain any of essential amino acid, could results in degradation of the body's proteins and other associated problems.
As plant and plant parts like leaves, flowers, fruits, seeds and vegetables are considered as rich source of free amino acids. Therefore these plant and plant parts could be used as natural and renewable sources to obtain these essential components. Also, in recent decades there has been found an immense interest in nutraceuticals, dietary health supplements and extracts which were obtained from natural sources in comparison to those with synthetic origin.
Tea (Camellia sinensis) of Theaceae family is known world wide as a beverage crop. This plant is also a good source of free amino acids. The amino acids content in the tea was estimated from 3-4% on dry wt. basis. The presence of free amino acids in tea is well known and it was reported that it contains all the 20 amino acids. The presence of different amino acids in tea like; alanine, arginine, asparagine, aspartic acid, glutamic acid, isoleucine, histidine, leucine, phenylalanine, serine, theanine, threonine, and tyrosine have been determined by amino acid analyzer as well as by HPLC analysis (Wang et al., Analysis of free amino acids in Chinese teas and flower of tea plant by high performance liquid chromatography combined with solid-phase extraction. Food Chemistry, 123, 2010, 1259-1266; Jean-Philippe Veyssier, Analysis of Theanine in Green Tea using the Biochrom 30 Amino Acid Analyser. Biochrom Ltd. Cambridge, UK; Ulrich H. Engelhardt, Chemistry of Tea, 2010 Elsevier Ltd.). Tea contains all the essential amino acids along with non-essential ones. Along with that, tea also contains a unique non-protein derived amino acid called as theanine which was formed from glutamine and ethylamine (Vuong et al., Journal of Science of Food and Agriculture, 2011, 91, 1931-1939).
Theanine is well known as a psychoactive amino acid which crosses the blood brain barrier and relaxes during stress. High water solubility of theanine in comparison to caffeine and catechins and its presence in sufficient amount in tea plant is an important requisite of the present invention; as it constitutes up to 50% of total amino acids present in the tea.
Though, Ekanayake et al. (U.S. patent application Ser. No. 10/689,910) has explained a process for isolation of theanine by extraction, absorption and filtration from plant material using isopropanol as a solvent to get theanine enriched extract. They used polyamides, polyvinylpyrollidine and polycar as adsorbants.
While, Tachiki et al. (U.S. patent application Ser. No. 10/523,098) has developed a synthetic method using glutaminase derived from the bacteria in a mixture of glutamine and ethylamine at alkaline pH (9-12).
Even there are few studies in literature which report sublimation process to obtain amino acids from natural samples (Daniel and Jeffrey, Analytical Chemistry 1998, 70, 3119-3122), but amino acid decomposition in to amines as well as deamination of amino acids at high temperature are the major problems in sublimation process.
Also according to Basiuk et al., there are more chances of formation of dipeptides and diketopiperazines in vapor phase of sublimation process. Also Fisher et al. (U.S. patent application Ser. No. 10/111,919) disclosed a process of purification of amino acids by electrodialysis followed by fermentation process to get amino acids.
Tea contains all the essential amino acids like, threonine, valine, leucine, isoleucine, lysine, phenylalanine and trytophan in it. So the present invention was specially focused on obtaining all these free amino acids present in tea along with theanine by an economical and green process methodology.
With ever increasing interest in naturally obtained food supplements, nutraceutiacls and additives: their market is also growing at very fast rate world wide. This might be due to health safety and therapeutic potential associated with them. So, in an attempt to obtain natural bio amino acids by a low cost green methodology and as an option for costlier protein supplements; the present invention was carried out.
As the free amino acids are readily available in the body and elevates its level in the general circulation within 15 minutes (Barry Finnin and Samuel Peters, Amino acids and Bodybuilding, Muscle and Fitness Magazine, April 1996) if consumed as supplements in comparison to protein supplements. Also, proteins first undergo enzymatic degradation in the alimentary canal for their catabolism into constituent free amino acids. So, in this invention we have disclosed an economical and green process for purification of free bio amino acids (theanine enriched) from tea shoots and from other plants and plant parts (renewable bioresources like leaves, fruits and flowers) which are good source of free amino acids.
There exist very few process methodologies which show extraction and purification of free amino acids from plant sources by green and economical process. While most of the earlier reported/developed processes and methodologies for purification of amino acids (ion exchange, sublimation, adsorption, electrodialysis etc.) generally involve usage of chemical substances, organic solvents, acids and alkali, leading to many disadvantages such as amino acid decomposition into amines as well as deamination of amino acids, the present invention totally excludes the use of all these chemical substances during the whole process of obtaining these natural bio amino acids.